U.S. patent application number 15/332220 was filed with the patent office on 2017-05-04 for base station apparatus and method.
This patent application is currently assigned to FUJITSU LIMITED. The applicant listed for this patent is FUJITSU LIMITED. Invention is credited to Shunsuke IIZUKA, Kazuya Kobayashi, Yoshiyuki Ono.
Application Number | 20170127357 15/332220 |
Document ID | / |
Family ID | 57345669 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170127357 |
Kind Code |
A1 |
Kobayashi; Kazuya ; et
al. |
May 4, 2017 |
BASE STATION APPARATUS AND METHOD
Abstract
An apparatus includes a memory and a processor coupled to the
memory. The processor is configured to execute reception
processing. The reception processing includes a process of
receiving a signal from a target terminal among a plurality of
terminals by a control channel adapted to multiplexing the signal
transmitted from the target terminal with one or more of signals
transmitted from any of the plurality of terminals except for the
target terminal, and a process of performing automatic frequency
control, based on the signal received from the target terminal, for
a data signal received from the target terminal. The processor is
configured to execute adjustment processing. The adjustment
processing includes a process of performing adjustment of a first
transmission power of the signal in the target terminal based on a
second transmission power of the one or more of signals in the any
of the plurality of terminals.
Inventors: |
Kobayashi; Kazuya;
(Kawasaki, JP) ; Ono; Yoshiyuki; (Komae, JP)
; IIZUKA; Shunsuke; (Kawasaki, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJITSU LIMITED |
Kawasaki-shi |
|
JP |
|
|
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
57345669 |
Appl. No.: |
15/332220 |
Filed: |
October 24, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/146 20130101;
H04W 72/0413 20130101; H04W 52/24 20130101; H04W 52/241 20130101;
H04W 72/0453 20130101; H04W 52/346 20130101; H04W 52/285
20130101 |
International
Class: |
H04W 52/24 20060101
H04W052/24; H04W 52/34 20060101 H04W052/34; H04W 72/04 20060101
H04W072/04; H04W 52/28 20060101 H04W052/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 2015 |
JP |
2015-215453 |
Claims
1. A base station apparatus, the apparatus comprising: a memory;
and a processor coupled to the memory and configured to execute
reception processing, the reception processing including a process
of receiving a predetermined signal from a target terminal device
among a plurality of terminal devices by a control channel, the
control channel being adapted to multiplex the predetermined signal
transmitted from the target terminal device with one or more
predetermined signals transmitted from any of the plurality of
terminal devices except for the target terminal device, and a
process of performing automatic frequency control, based at least
in part on the predetermined signal received from the target
terminal device, for a data signal received from the target
terminal device, and execute adjustment processing, the adjustment
processing including a process of performing adjustment of a first
transmission power of the predetermined signal in the target
terminal device based at least in part on a second transmission
power of the one or more predetermined signals in the any of the
plurality of terminal devices.
2. The base station apparatus according to claim 1, wherein in a
case that reception quality of the data signal subjected to the
automatic frequency control by the reception processing is lower
than a predetermined reception quality, the second transmission
power used in the adjustment processing is a transmission power
having a largest transmission power among the one or more
predetermined signals transmitted from the any of the plurality of
terminal devices.
3. The base station apparatus according to claim 2, wherein the
adjustment processing includes performing the adjustment of
increasing the first transmission power of the predetermined signal
in the target terminal device such that the first transmission
power of the predetermined signal becomes equal to the second
transmission power having a largest transmission power among the
one or more predetermined signals transmitted from the any of the
plurality of terminal devices.
4. The base station apparatus according to claim 2, wherein the
adjustment processing includes in a case that none of the one or
more of predetermined signals have a transmission power higher than
the transmission power of the predetermined signal in the target
terminal device, not performing the adjustment even when the
reception quality of the data signal subjected to the automatic
frequency control by the reception processing unit is lower than
the predetermined reception quality.
5. The base station apparatus according to claim 2, wherein the
adjustment processing includes in a case that the target terminal
device is moving at a speed equal to or higher than at a
predetermined speed, not performing the adjustment even when
reception quality of the data signal is lower than the
predetermined reception quality.
6. The base station apparatus according to claim 1, wherein the
adjustment processing includes in a case that reception quality of
the data signal subjected to the automatic frequency control by the
reception processing is equal to or higher than a predetermined
reception quality while transmission power of the predetermined
signal in the target terminal device is largest among transmission
powers of the one or more predetermined signals in the any of the
plurality of terminal devices, performing adjustment of decreasing
the transmission power of the predetermined signal in the target
terminal device.
7. The base station apparatus according to claim 1, wherein the
adjustment processing includes when the adjustment of the
transmission power of the predetermined signal in the target
terminal device is performed, comparing reception qualities of the
data signal subjected to the automatic frequency control by the
reception processing before and after the adjustment with each
other, and, based at least in part on a result of the comparison,
restoring the transmission power of the predetermined signal in the
target terminal device to the transmission power of the
predetermined signal in the target terminal device before the
adjustment.
8. The base station apparatus according to claim 1, wherein the
adjustment processing includes when adjusting the transmission
power of the predetermined signal in the target terminal device,
setting adjustment speed of the transmission power of the
predetermined signal in the target terminal device based at least
in part on a type of the data signal from the target terminal
device to the base station apparatus.
9. The base station apparatus according to claim 1, wherein the
adjustment processing includes when adjusting the transmission
power of the predetermined signal in the target terminal device,
setting adjustment speed of the transmission power of the
predetermined signal in the target terminal device based at least
in part on a type of the data signal from the target terminal
device to the base station apparatus and a type of a data signal
from the any of the plurality of terminal devices to the base
station apparatus.
10. The base station apparatus according to claim 1, wherein the
adjustment processing includes when adjusting the transmission
power of the predetermined signal in the target terminal device,
setting adjustment speed of the transmission power of the
predetermined signal in the target terminal device based at least
in part on a number of times the adjustment processing for the
target terminal device is executed.
11. The base station apparatus according to claim 1, wherein the
adjustment processing includes performing the adjustment of each of
the plurality of terminal devices, and when adjusting transmission
power of the predetermined signal in the target terminal device,
setting adjustment speed of the transmission power of the
predetermined signal in the target terminal device based at least
in part on a number of times the adjustment processing for the
target terminal device is executed and a number of times the
adjustment processing for each of the any of the plurality of
terminal devices.
12. The base station apparatus according to claim 1, wherein the
control channel includes a physical uplink control channel (PUCCH),
and wherein the predetermined signal includes a channel quality
indicator (CQI).
13. A method for a base station apparatus, the method comprising:
executing reception processing, the reception processing including
a process of receiving a predetermined signal from a target
terminal device among a plurality of terminal devices by a control
channel, the control channel being adapted to multiplexing the
predetermined signal transmitted from the target terminal device
with one or more of a plurality of predetermined signals
transmitted from any of the plurality of terminal devices except
for the target terminal device, and a process of performing
automatic frequency control, based at least in part on the
predetermined signal received from the target terminal device, for
a data signal received from the target terminal device, and
executing adjustment processing, the adjustment processing
including a process of performing adjustment of a first
transmission power of the predetermined signal in the target
terminal device based at least in part on a second transmission
power of the one or more of predetermined signals in the any of the
plurality of terminal devices.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2015-215453,
filed on Nov. 02, 2015, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The present disclosure relates generally to wireless
communication, and more specifically a base station apparatus
capable of wirelessly communicating with a plurality of user
terminals.
BACKGROUND
[0003] Conventionally, a technique is known that adjusts
transmission power of a signal in a radio communication system when
throughput of a reception signal drops. Also, automatic frequency
control (AFC) is known that compensates for frequency deviation of
a transmission signal from a terminal device by using a signal
periodically transmitted from the terminal device to a base station
apparatus. As the signal periodically transmitted from the terminal
device to the base station apparatus, for example, a channel
quality indicator (CQI) is used.
[0004] As examples of the prior art, Japanese Laid-open Patent
Publication No. 2014-49841, Japanese Laid-open Patent Publication
No. H07-107033, Japanese Laid-open Patent Publication No.
2014-127976, Japanese Laid-open Patent Publication No. 2011-160376,
and International Publication Pamphlet No. WO2006/085365 are
known.
SUMMARY
[0005] According to an aspect of the invention, an apparatus
includes a memory and a processor coupled to the memory. The
processor included in the apparatus is configured to execute
reception processing. The reception processing includes a process
of receiving a predetermined signal from a target terminal device
among a plurality of terminal devices by a control channel, the
control channel being adapted to multiplexing the predetermined
signal transmitted from the target terminal device with one or more
of predetermined signals transmitted from any of the plurality of
terminal devices except for the target terminal, and a process of
performing automatic frequency control, based at least in part on
the predetermined signal received from the target terminal device,
for a data signal received from the target terminal device. The
processor included in the apparatus is configured to execute
adjustment processing. The adjustment processing includes a process
of performing adjustment of a first transmission power of the
predetermined signal in the target terminal device based at least
in part on a second transmission power of the one or more of
predetermined signals in the any of the plurality of terminal
devices.
[0006] The object and advantages of the invention will be realized
and attained by means of the elements and combinations particularly
pointed out in the claims.
[0007] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 illustrates an example of a communication system
according to an embodiment;
[0009] FIG. 2 illustrates an example of a base station apparatus
according to the embodiment;
[0010] FIG. 3 illustrates an example of a hardware configuration of
the base station apparatus according to the embodiment;
[0011] FIG. 4 illustrates an example of a terminal device according
to the embodiment;
[0012] FIG. 5 illustrates an example of a hardware configuration of
the terminal device according to the embodiment;
[0013] FIG. 6 illustrates an example of a radio communication
system according to the embodiment;
[0014] FIG. 7 illustrates an example of a UE movement in the radio
communication system according to the embodiment;
[0015] FIG. 8 illustrates an example of an uplink bandwidth in the
radio communication system according to the embodiment;
[0016] FIG. 9 illustrates an example of an interference of a PUCCH
in the radio communication system according to the embodiment;
[0017] FIG. 10 illustrates an example of a processing timing in the
radio communication system according to the embodiment;
[0018] FIG. 11 is a flowchart illustrating an example of a power
adjustment processing by an eNB according to the embodiment;
[0019] FIG. 12 is a flowchart illustrating an example of a
processing of adjustment of increasing a CQI transmission power of
a target UE by the eNB according to the embodiment;
[0020] FIG. 13 is a flowchart illustrating an example of a
processing of power adjustment (up) based on a target power by the
eNB according to the embodiment;
[0021] FIG. 14 is a flowchart illustrating an example of another
processing of power adjustment (up) based on the target power by
the eNB according to the embodiment;
[0022] FIG. 15 is a flowchart illustrating an example of a
processing of adjustment of decreasing the CQI transmission power
of the target UE by the eNB according to the embodiment;
[0023] FIG. 16 is a flowchart illustrating an example of a power
adjustment (down) processing by the eNB according to the
embodiment;
[0024] FIG. 17 is a flowchart illustrating an example of a power
adjustment check processing by the eNB according to the embodiment
(Part 1);
[0025] FIG. 18 is a flowchart illustrating an example of a power
adjustment check processing by the eNB according to the embodiment
(Part 2); and
[0026] FIG. 19 is a diagram illustrating an example of information
of UEs stored by the eNB according to the embodiment.
DESCRIPTION OF EMBODIMENTS
[0027] The conventional techniques mentioned have a problem that,
for example, when CQIs from many terminal devices are multiplexed
in high density in the same timing of the uplink control channel,
interference among the CQIs increases and thereby causes decrease
in the AFC accuracy based on the CQI.
[0028] According to an aspect of the present disclosure, it is an
object of the technique disclosed herein to reduce decrease in the
accuracy of the AFC. Hereinafter, embodiments of the base station
apparatus according to the present disclosure are described in
detail with reference to the accompanying drawings.
[0029] FIG. 1 is a diagram illustrating an example of a
communication system according to the embodiment. As illustrated in
FIG. 1, a communication system 100 according to the embodiment
includes a base station apparatus 110 and terminal devices 121,
122, . . . . The terminal devices 121, 122, . . . are terminal
devices capable of performing radio communication with the base
station apparatus 110. An example depicted in FIG. 1 illustrates a
state in which a plurality of terminal devices (the terminal
devices 121, 122, . . . ) perform radio communication with the base
station apparatus 110. The number of terminal devices performing
radio communication with the base station apparatus 110 may be one
or zero depending on the movement state of each terminal
device.
[0030] Also, the terminal devices 121, 122, . . . are terminal
devices which multiplex and transmit a predetermined signal to the
base station apparatus 110 through an uplink control channel in the
same timing. For example, the base station apparatus 110 sets, to
each terminal device coupling to the cell thereof, a timing of
transmitting a predetermined signal to the base station apparatus
110.
[0031] In this case, the terminal devices 121, 122, . . . are
terminal devices to which the same timing is set by the base
station apparatus 110, among terminal devices coupled to the cell
of the base station apparatus 110.
[0032] The uplink control channel is, by way of an example, a
physical uplink control channel (PUCCH). The predetermined signal
is, for example, a control signal which is periodically transmitted
from the terminal devices 121, 122, . . . to the base station
apparatus 110 through the uplink control channel. By way of an
example, the predetermined signal is CQI. In the description below,
the uplink control channel is a PUCCH, and the predetermined signal
is a signal including CQI.
[0033] The base station apparatus 110 comprises a reception
processing unit 111 and an adjustment unit 112. The reception
processing unit 111 receives the CQI from a target terminal device
among the terminal devices 121, 122, . . . through a PUCCH. The
target terminal device is a terminal device for which transmission
power of the CQI is adjusted. In this case, assume that the
terminal device 121 out of the terminal devices 121, 122, . . . is
a target terminal device.
[0034] The reception processing unit 111 performs the AFC for a
data signal received from the terminal device 121 based on the CQI
received from the terminal device 121. For example, the reception
processing unit 111 estimates frequency deviation of the CQI
received from the terminal device 121. The frequency deviation is a
deviation from the target value in the frequency of the signal
transmitted from the terminal device 121 to the base station
apparatus 110. The deviation is caused, for example, due to low
accuracy of the oscillator used for generating the transmission
signal.
[0035] The reception processing unit 111 compensates for the
frequency deviation in the data signal received from the terminal
device 121 based on the estimated frequency deviation. Thus, the
frequency deviation in the data signal received from the terminal
device 121 may be compensated for, and thereby reception quality of
the data signal may be improved. The reception processing unit 111
may notify the adjustment unit 112 of the reception quality based
on demodulation result of the data signal whose the frequency
deviation is compensated for.
[0036] The adjustment unit 112 adjusts transmission power of the
CQI in the terminal device 121, based on the transmission power of
the CQI in the terminal devices 122, . . . among the terminal
devices 121, 122, . . . , which is different from the terminal
device 121. At that time, the adjustment unit 112 may adjust
transmission power of CQI in the terminal device 121 or
transmission power of the PUCCH including the CQI in the terminal
device 121, and may not adjust transmission power of the data
signal in the terminal device 121.
[0037] For example, when reception quality notified by the
reception processing unit 111 is lower than a predetermined
reception quality, the adjustment unit 112 identifies a terminal
device having a largest transmission power of the CQI among the
terminal devices 122, . . . . Then, the adjustment unit 112
performs adjustment of increasing the CQI transmission power in the
terminal device 121 based on the CQI transmission power in the
identified terminal device. By way of an example, the adjustment
unit 112 performs adjustment of increasing the CQI transmission
power in the terminal device 121 such that the CQI transmission
power in the terminal device 121 becomes equal to (closer to) the
CQI transmission power of the identified terminal device.
[0038] Further, when reception quality notified by the reception
processing unit 111 is higher than a predetermined reception
quality, the adjustment unit 112 may perform adjustment of
decreasing the CQI transmission power in the terminal devices 121.
In this case, for example, when the CQI transmission power in the
terminal device 121 is largest among CQIs of the terminal devices
121, 122, . . . , the adjustment unit 112 performs adjustment of
decreasing the CQI transmission power in the terminal device 121.
Further, when the CQI transmission power in the terminal device 121
is not largest among CQIs of the terminal devices 121, 122, . . . ,
the adjustment unit 112 may not perform the adjustment of
decreasing the CQI transmission power in the terminal device
121.
[0039] As described above, the base station apparatus 110 according
to the embodiment adjusts the CQI transmission power from the
terminal device 121 based on the CQI transmission power from the
terminal devices 122, . . . whose CQI transmission timing is the
same as the terminal device 121. Thus, transmission powers of CQIs
multiplexed in the same timing may be matched, and thereby
interference among CQIs due to difference in the transmission power
of CQIs multiplexed in the same timing may be reduced. Thus,
decrease in the AFC accuracy based on the CQI may be
suppressed.
[0040] The reception processing unit 111 and the adjustment unit
112 of the base station apparatus 110 may be formed as the same
circuit or as a separate circuit respectively. Alternatively, the
reception processing unit 111 and the adjustment unit 112 may be
mounted in the base station apparatus 110 as one or more integrated
circuits in which circuits corresponding to those components are
integrated. Those components of the base station apparatus 110 may
be a function module implemented by a computer program executed on
a processor of the base station apparatus 110. For example, with a
computer program stored in a memory of the base station apparatus
110 being executed on one or more processors, one or more
processors of the base station apparatus 110 may operate as a
hardware circuit which is capable of executing a whole or a part of
processes of components illustrated in FIG. 1. For example, the
processor of the base station apparatus 110 includes a central
processing unit (CPU), a micro processing unit (MPU), and a
field-programmable gate array (FPGA). The processor may be a
multiprocessing unit incorporating multiple processor cores or may
be any processor core incorporated into the multiprocessing unit.
An example of those processors is illustrated in FIG. 3.
[0041] Although adjustment of the CQI transmission power is
described based on the terminal device 121 among the terminal
devices 121, 122, . . . as the target terminal device, the
adjustment unit 112 also may adjust the CQI transmission power by
using a terminal device out of the terminal devices 122, . . . as
the target terminal device.
[0042] FIG. 2 illustrates an example of a base station apparatus
according to the embodiment. As illustrated in FIG. 2, the base
station apparatus 110 according to the embodiment comprises base
band processing units 201, 205, a transmission RF processing
unit/RRH unit 202, an antenna 203, a reception RF processing
unit/RRH unit 204, a scheduler 206, and an apparatus control unit
207.
[0043] The base band processing unit 201 performs base band
processing for a downlink (DL) transmission signal which the base
station apparatus 110 transmits, and outputs a DL base band signal
obtained by the base band processing to the transmission RF
processing unit/RRH unit 202. Further, the base band processing
unit 201 performs the base band processing based on DL scheduling
information and uplink (UL) control information notified by the
scheduler 206. The UL control information includes a transmission
power control (TPC) value instructing, for example, an adjustment
to the CQI transmission power with respect to the terminal devices
121, 122, . . . . The base band processing unit 201 gives the UL
control information outputted from the scheduler 206 to the DL base
band signal.
[0044] The transmission RF processing unit/RRH unit 202 performs RF
processing and remote radio head (RRH) processing for the DL base
band signal outputted from the base band processing unit 201. For
example, the transmission RF processing unit/RRH unit 202 performs
transmission RF processing for the DL base band signal outputted
from the base band processing unit 201, such as conversion from the
digital signal to the analog signal and conversion and
amplification from the base band frequency to the RF frequency.
Then, the transmission RF processing unit/RRH unit 202 outputs the
DL signal obtained by the transmission RF processing to the antenna
203.
[0045] When the antenna 203 is located apart from a main body of
the base station apparatus 110, the transmission RF processing
unit/RRH unit 202 is a RRH installed apart from the main body of
the base station apparatus 110, along with the antenna 203. In this
case, the DL base band signal outputted from the base band
processing unit 201 is transmitted to the transmission RF
processing unit/RRH unit 202 via interface such as a common public
radio interface (CPRI). The transmission RF processing unit/RRH
unit 202 performs the transmission RF processing for the DL base
band signal transmitted via interface. Then, the transmission RF
processing unit/RRH unit 202 outputs the DL signal obtained by the
transmission RF processing to the antenna 203.
[0046] The antenna 203 transmits the DL signal outputted from the
transmission RF processing unit/RRH unit 202 to the terminal
devices 121, 122, . . . by radio. Further, the antenna 203 receives
a UL signal transmitted from the terminal devices 121, 122, . . .
by radio and outputs the received UL signal to the reception RF
processing unit/RRH unit 204.
[0047] The reception RF processing unit/RRH unit 204 performs RF
processing and RRH processing for the UL signal outputted from the
antenna 203. For example, the reception RF processing unit/RRH unit
204 performs reception RF processing for the UL signal outputted
from the antenna 203, such as amplification, conversion from the RF
frequency to the base band frequency, and conversion from the
analog signal to the digital signal. Then, the reception RF
processing unit/RRH unit 204 outputs the UL base band signal
obtained by the reception RF processing to the base band processing
unit 205.
[0048] When the antenna 203 is located apart from the main body of
the base station apparatus 110, the reception RF processing
unit/RRH unit 204 is a RRH installed apart from the main body of
the base station apparatus 110, along with the antenna 203. In this
case, the UL base band signal obtained by the reception RF
processing in the reception RF processing unit/RRH unit 204 is
transmitted to the base band processing unit 205 via interface such
as CPRI.
[0049] The base band processing unit 205 performs base band
processing for the UL base band signal outputted from the reception
RF processing unit/RRH unit 204. The base band processing by the
base band processing unit 205 includes the AFC which estimates a
frequency deviation in the signal from the base station apparatus
110 and compensates for, based on an estimated frequency deviation,
the frequency deviation in the signal from the base station
apparatus 110. Further, the base band processing unit 205 performs
base band processing based on UL scheduling information notified by
the scheduler 206. The base band processing unit 205 outputs a
reception signal obtained by base band processing.
[0050] The scheduler 206 performs uplink (UP) and downlink (DL)
scheduling in the base station apparatus 110. Then, the scheduler
206 outputs DL scheduling information indicating the result of the
downlink scheduling to the base band processing unit 201. Further,
the scheduler 206 outputs UL scheduling information indicating the
result of the uplink scheduling to the base band processing unit
205.
[0051] Further, the scheduler 206 performs a process of adjusting
the CQI transmission power by the terminal devices 121, 122, . . .
for the uplink. For example, the scheduler 206 generates a TPC
value for adjusting CQI transmission power by the terminal devices
121, 122, . . . , based on reception quality of a reception signal
obtained by the AFC of the base band processing unit 205. Then, the
scheduler 206 outputs UL control information including the
generated TPC value to the base band processing unit 201 and
thereby transmits UL control information including the TPC value to
the terminal devices 121, 122,
[0052] The apparatus control unit 207 controls operation of
processing units of the base station apparatus 110 such as the base
band processing unit 201, the transmission RF processing unit/RRH
unit 202, the reception RF processing unit/RRH unit 204, the base
band processing unit 205, and the scheduler 206.
[0053] The reception processing unit 111 illustrated in FIG. 1 may
be implemented, for example, by the base band processing unit 205.
The adjustment unit 112 illustrated in FIG. 1 may be implemented,
for example, by the scheduler 206.
[0054] FIG. 3 is a diagram illustrating an example of a hardware
configuration of the base station apparatus according to the
embodiment. As illustrated in FIG. 3, the base station apparatus
110 according to the embodiment comprises antennas 301, 302, an
interface circuit 303, a RF circuit 304, DSPs 311, 321, and FPGAs
312, 332, 341. Further, the base station apparatus 110 comprises
memories 313, 322, 333, a CPU 331, a DAC/ADC 342, a mixer 343, and
a PA/LNA 344.
[0055] The interface circuit 303 is a circuit which implements an
interface coupling the RF circuit 304, the FPGA 312, the DSP 321,
the CPU 331, and the FPGA 332 with each other. DSPs 311, 321 are
digital signal processors (DSP) configured to perform arithmetic
operation by using the memory 313 and the memory 322 respectively.
The FPGAs 312, 332 are field programmable gate arrays (FPGA)
configured to perform arithmetic operation by using the memory 313
and the memory 333 respectively. The CPU 331 is a central
processing unit (CPU) configured to perform arithmetic operation by
using the memory 333.
[0056] Each of the memories 313, 322, 333 includes, for example, a
main memory and an auxiliary memory. The main memory is, for
example, a random access memory (RAM). The main memory is used as a
work area of the DSPs 311, 321 or the CPU 331. The auxiliary memory
is a non-volatile memory such as, for example, a magnetic disk, an
optical disk and a flush memory. The auxiliary memory stores
programs for operating the base station apparatus 110. Programs
stored in the auxiliary memory are loaded into the main memory and
executed by the DSPs 311, 321 or the CPU 331.
[0057] The antenna 203 illustrated in FIG. 2 may be implemented,
for example, by either of the antennas 301, 302. For example, in a
case where the antenna 203 is provided in the vicinity of the main
body of the base station apparatus 110, the antenna 203 may be
implemented by the antenna 301. Also, in a case where the antenna
203 is provided apart from the main body of the base station
apparatus 110, the antenna 203 may be implemented by the antenna
302.
[0058] The base band processing units 201, 205 illustrated in FIG.
2 may be implemented, for example, by the DSP 311, the FPGA 312 and
the memory 313. The scheduler 206 illustrated in FIG. 2 may be
implemented, for example, by the DSP 321 and the memory 322. The
apparatus control unit 207 illustrated in FIG. 2 may be
implemented, for example, by the CPU 331, the FPGA 332 and the
memory 333.
[0059] When performing radio communication with the terminal
devices 121, 122, . . . by the antenna 301, the transmission RF
processing unit/RRH unit 202 illustrated in FIG. 2 may be
implemented, for example, by the RF circuit 304. For example, the
RF circuit 304 includes circuits of devices such as converters and
amplifiers performing transmission RF processing by the
transmission RF processing unit/RRH unit 202 and reception RF
processing by the reception RF processing unit/RRH unit 204
illustrated in FIG. 2. In this case, the antenna 301 transmits the
DL signal outputted from the RF circuit 304 to the terminal devices
121, 122, . . . by radio. Further, the antenna 301 receives the UL
signal transmitted from the terminal devices 121, 122, . . . by
radio and outputs the received UL signal to the RF circuit 304.
[0060] When performing radio communication with the UE by the
antenna 302, the transmission RF processing unit/RRH unit 202
illustrated in FIG. 2 may be implemented, for example, by the FPGA
341, the DAC/ADC 342, the mixer 343, and the PA/LNA 344. The FPGA
341 receives, via interface such as the CPRI, a DL base band signal
outputted from the DSP 311 or the FPGA 312 via the interface
circuit 303, and outputs the received DL base band signal to the
DAC/ADC 342. Further, the FPGA 341 transmits, via interface such as
the CPRI, an UL base band signal outputted from the DAC/ADC 342 to
the DSP 311 or the FPGA 312 via the interface circuit 303.
[0061] The DAC/ADC 342 includes a digital/analog converter (DAC)
which converts the DL base band signal outputted from the FPGA 341
from the digital signal to the analog signal. The DAC/ADC 342
outputs the DL base band signal converted to the analog signal by
the DAC to the mixer 343. The DAC/ADC 342 also includes an
analog/digital converter (ADC) which converts the UL base band
signal outputted from the mixer 343 from the analog signal to the
digital signal. The DAC/ADC 342 outputs the UL base band signal
converted to the digital signal by the ADC to the FPGA 341.
[0062] The mixer 343 converts the DL base band signal outputted
from the DAC/ADC 342 from the base band frequency to the RF
frequency, and outputs the DL signal converted to the RF frequency
to the PA/LNA 344. The mixer 343 converts the UL base band signal
outputted from the PA/LNA 344 from the RF frequency to the base
band frequency, and outputs the UL base band signal converted to
the base band frequency to the DAC/ADC 342.
[0063] The PA/LNA 344 includes a power amplifier (PA) which
amplifies the DL signal outputted from the mixer 343. The PA/LNA
344 outputs the DL signal amplified by the PA to the antenna 302.
The PA/LNA 344 also includes a low noise amplifier (LNA) which
amplifies the UL signal outputted from the antenna 302. The PA/LNA
344 outputs the UL signal amplified by the LNA to the mixer
343.
[0064] The antenna 302 transmits the DL signal outputted from the
PA/LNA 344 to the terminal devices 121, 122, . . . by radio.
Further, the antenna 302 receives the UL signal transmitted from
the terminal devices 121, 122, . . . by radio and outputs the
received UL signal to the PA/LNA 344.
[0065] FIG. 4 is a diagram illustrating an example of a terminal
device according to the embodiment. Although configuration of the
terminal device 121 is described below, the terminal devices 122, .
. . have the same configuration. As illustrated in FIG. 4, the
terminal device 121 according to the embodiment comprises an
application unit 401, a base band transmission and reception
processing unit 402, a RF processing unit 403 and an antenna
404.
[0066] The application unit 401 generates a transmission signal
which the terminal device 121 transmits, and outputs to the base
band transmission and reception processing unit 402. Further, the
application unit 401 performs a processing based on a reception
signal outputted from the base band transmission and reception
processing unit 402.
[0067] The base band transmission and reception processing unit 402
performs base band processing for a transmission signal outputted
from the application unit 401, and outputs a DL base band signal
obtained by base band processing to the RF processing unit 403. The
base band transmission and reception processing unit 402 also
performs base band processing for an UL base band signal outputted
from the RF processing unit 403, and outputs a reception signal
obtained by base band processing to the application unit 401.
[0068] Further, the base band transmission and reception processing
unit 402 acquires a TPC value from the base station apparatus 110
out of UL control information included in the reception signal
obtained by base band processing. Then, the RF processing unit 403
adjusts, in accordance with the acquired TPC value, the CQI
transmission power included in the UL signal transmitted to the
base station apparatus 110 by the terminal device 121.
[0069] The RF processing unit 403 performs RF processing for the DL
base band signal outputted from the base band transmission and
reception processing unit 402. For example, the RF processing unit
403 performs transmission RF processing for the DL base band signal
outputted from the base band transmission and reception processing
unit 402, such as conversion from the digital signal to the analog
signal and conversion and amplification from the base band
frequency to the RF frequency. Then, the RF processing unit 403
outputs the DL signal obtained by the transmission RF processing to
the antenna 404.
[0070] Further, the reception RF processing unit 403 performs RF
processing for the UL signal outputted from the antenna 404. For
example, the RF processing unit 403 performs reception RF
processing for the UL signal outputted from the antenna 404, such
as amplification, conversion from the RF frequency to the base band
frequency, and conversion from the analog signal to the digital
signal. Then, the RF processing unit 403 outputs the UL base band
signal obtained by the reception RF processing to the base band
transmission and reception processing unit 402.
[0071] The antenna 404 transmits the DL signal outputted from the
RF processing unit 403 to the base station apparatus 110 by radio.
Further, the antenna 404 receives the UL signal transmitted from
the base station apparatus 110 by radio and outputs the received UL
signal to the RF processing unit 403.
[0072] FIG. 5 is a diagram illustrating an example of a hardware
configuration of a terminal device according to the embodiment.
Although hardware configuration of the terminal device 121 is
described below, the terminal devices 122, . . . have the same
configuration. As illustrated in FIG. 3, the terminal device 121
according to the embodiment comprises an antenna 501, a RF circuit
502, an interface circuit 503, a CPU 504 and a memory 505.
[0073] The antenna 501 transmits and receives a radio signal from
the base station apparatus 110. The RF circuit 502 includes
circuits of devices such as converters and amplifiers performing
transmission RF processing and reception RF processing by the RF
processing unit 403 illustrated in FIG. 4. The interface circuit
503 is a circuit which implements an interface coupling the RF
circuit 502 and the CPU 504 with each other. The CPU 504 performs
arithmetic operation by using the memory 505. The memory 505
includes, for example, a main memory and an auxiliary memory. The
main memory is, for example, a RAM. The main memory is used as a
work area of the CPU 504. The auxiliary memory is a non-volatile
memory such as, for example, a magnetic disk and a flush memory.
The auxiliary memory stores programs for operating the terminal
device 121. Programs stored in the auxiliary memory are loaded into
the main memory and executed by the CPU 504.
[0074] The antenna 404 illustrated in FIG. 4 may be implemented,
for example, by the antenna 501. The RF processing unit 403
illustrated in FIG. 4 may be implemented, for example, by the RF
circuit 502. The base band transmission and reception processing
unit 402 illustrated in FIG. 4 may be implemented, for example, by
the CPU 504 and the memory 505.
[0075] FIG. 6 is a diagram illustrating an example of a radio
communication system according to the embodiment. The communication
system 100 illustrated in FIG. 1 may be applied, for example, to a
radio communication system 600 illustrated in FIG. 6. The radio
communication system 600 includes an eNB 610, a femto base station
614, UEs 631 to 636 and UE groups 641 to 643.
[0076] The base station apparatus 110 illustrated in FIG. 1 may be
applied, by way of an example, to an eNB 610 and a femto base
station 614. The terminal devices 121, 122, . . . illustrated in
FIG. 1 may be applied, by way of an example, to a UE among UEs 631
to 635 and a UE among UE groups 641 to 643.
[0077] The eNB 610 is a base station apparatus (evolved node B)
comprising the antenna 611 and RRHs 612, 613, 615, 616. For
example, the eNB 610 forms a cell 601 of a frequency f1 by the
antenna 611. The eNB 610 also forms a cell 602 of a frequency f2 by
the RRH 612. The eNB 610 also forms a cell 603 of a frequency f2 by
the RRH 613. The eNB 610 also forms a cell 605 of a frequency f2 by
the RRH 615. The eNB 610 also forms a cell 606 of a frequency f2 by
the RRH 616. The femto base station 614 is a base station apparatus
which forms a cell 604 of a frequency f3.
[0078] The cell 601 is a macro cell with a wide cell range. Cells
602, 603, 605, 606 are small cells with the cell range smaller than
the macro cell. The cell 604 is a femto cell with the cell range
smaller than the macro cell. In the example illustrated in FIG. 6,
each cell range of cells 602 to 606 is included in the cell range
of the cell 601.
[0079] UEs 631 to 635 are, for example, terminal devices (UE: User
Equipment) which are capable of performing radio communication by
cells 601 to 606. In the example illustrated in FIG. 6, the UE 631
stays inside the cell 601 only and performs downlink and uplink
radio communication by the cell 601. The UE 632 stays inside cells
601, 602, performs downlink radio communication by carrier
aggregation by using both cells 601 and 602, and performs uplink
radio communication by the cell 602.
[0080] The UE 633 stays inside cells 601, 603 and performs downlink
and uplink radio communication by the cell 603. The UE 634 stays
inside cells 601, 604 and performs downlink and uplink radio
communication by the cell 604. The UE 635 stays inside cells 601,
605, performs downlink radio communication by carrier aggregation
by using both cells 601 and 605, and performs uplink radio
communication by the cell 605. In the example illustrated in FIG.
6, in addition to UEs 631 to 635, there are, for example, the UE
group 641 staying inside the cell 602, the UE group 642 staying
inside the cell 603, and the UE group 643 staying inside the cell
605.
[0081] For example, UEs 631 to 635 transmit the CQI to the eNB 610
or the femto base station 614 by the PUCCH in the uplink radio
communication. The eNB 610 and the femto base station 614 perform
the AFC for the PUSCH received from UEs 631 to 635 based on the
received CQI.
[0082] FIG. 7 is a diagram illustrating an example of a UE movement
in the radio communication system according to the embodiment. In
FIG. 7, description of a section similar to the section illustrated
in FIG. 6 is omitted by assigning the same reference numeral. For
example, in a case where cells with frequencies same or close to
each other are densely formed and there are many UEs like in a
radio communication system 600 illustrated in FIG. 6, a moving UE
repeats entry and exit from cells in different environments. Entry
and exit from cells includes repetition of handover between cells
and mere passage through the area of cells.
[0083] In the example illustrated in FIG. 7, the UE 631 moves from
a position staying inside the cell 601 to a position staying inside
cells 601, 602, then moves to a position staying inside cells 601,
603 and then moves to a position staying inside the cell 601
only.
[0084] FIG. 8 is a diagram illustrating an example of an uplink
bandwidth in the radio communication system according to the
embodiment. A bandwidth 800 illustrated in FIG. 8 represents a
bandwidth in an uplink of the radio communication system 600. The
transverse direction of the bandwidth 800 represents frequency.
PUCCHs 801, 802 represent PUCCHs allocated to the bandwidth 800.
The PUSCH 803 represents a physical uplink shared channel (PUSCH)
allocated to the bandwidth 800. As illustrated in FIG. 8, the
bandwidth in the bandwidth 800 to which the PUCCHs 801, 802 are
allocated is limited.
[0085] In a case where cells with frequencies same or close to each
other are densely formed and there are many UEs like in a radio
communication system 600 illustrated in FIG. 6, many UEs are
multiplexed (for example, code division multiplexed) in limited
resources of PUCCHs 801, 802. If many UEs are multiplexed, accurate
extraction of PUCCH destined to the station becomes difficult, and
thereby reception quality of the PUCCH is apt to deteriorate and
accuracy of AFC based on the CQI included in the PUCCH drops.
[0086] FIG. 9 is a diagram illustrating an example of a PUCCH
interference in a radio communication system according to the
embodiment. In FIG. 9, the UE signal 901 is a PUCCH signal of the
UE 631, and the UL signal 902 is a PUCCH signal of the UE 632. For
example, when the UE 631 enters the cell 602 as in the example
illustrated in FIG. 7, the UE 631 maintains transmission power then
existing in the cell 601 until the UE 631 becomes steady.
[0087] Therefore, as illustrated in FIG. 9, when transmission power
of the UL signal 901 in the cell 601 is higher than transmission
power of the UL signal 902, the UL signal 901 of the UE 631 may
become an interference wave against the UL signal 902 (desired
wave) of the UE 632. On the other hand, although not illustrated,
when transmission power of the UL signal 901 in the cell 601 is
lower than transmission power of the UL signal 902, the UL signal
902 of the UE 632 may become an interference wave against the UL
signal 901 (desired wave) of the UE 631.
[0088] Thus, the resource of the PUCCH is just a few RB in each
bandwidth, and when multiple UEs are multiplexed therein, the PUCCH
is apt to deteriorate. In such an overcrowded environment, when
there is a high inbound and outbound traffic in the cell of the UE,
desired wave of a UE may become an interference wave against other
UEs and may cause decrease in the AFC accuracy.
[0089] Here, decrease in the AFC accuracy due to multiplexing of
many CQIs is described. For example, although the eNB 610 performs
the AFC using the PUCCH including the CQI, turbo encoding is not
used for the PUCCH. In the PUCCH, information for multiplexing
multiple UEs is stored in the 1 RB by using orthogonal series and
cyclic shift. For example, in the format 1x, information for
multiplexing 32 UEs is stored in 1 RB by using the cyclic shift. In
the format 2x, information for multiplexing 12 UEs is stored in 1
RB. In the format 3, information for multiplexing 5 UEs is stored
in 1 RB by using an orthogonal series.
[0090] Information of the PUCCH in that state is processed by the
eNB 610, and each UE acquires a signal of the base station thereof.
Therefore, if the signal wave of a UE among the multiplexed
multiple UEs is strong, it interferes with and affects the PUCCH
information of other UEs multiplexed adjacent to the UE since AFC
for other UEs is performed based on the PUCCH information subjected
to the interference, accuracy of the AFC drops. Larger the number
of multiplexed UEs, more accuracy of the AFC is apt to deteriorate
since each of UEs is multiplexed close to the RB and thereby there
is a high possibility that the hamming distance may become
short.
[0091] FIG. 10 is a diagram illustrating an example of a processing
timing in the radio communication system according to the
embodiment. In FIG. 10, adjustment of the CQI transmission power
from the UE 632 by the eNB 610 is described by way of an example. A
radio resource illustrated in FIG. 10 is a radio resource in the
radio communication system 600, and the transverse direction of the
radio resource 1000 represents time.
[0092] A frame 1010 represents a unit of 1 frame in the radio
resource 1000. 1 sub-frame corresponds to 10 [ms]. A sub-frame 1020
represents a unit of 1 sub-frame in the radio resource 1000. 1
sub-frame corresponds to 1 [ms]. A slot 1030 represents a unit of 1
slot in the radio resource 1000. 1 slot corresponds to 0.5 [ms]. A
resource block 1050 is a frequency resource (systems BW, RB) in the
radio resource 1000.
[0093] In the example illustrated in FIG. 10, assume that the eNB
610 sets CQI transmission timings 1061, 1062, . . . of a third
symbol in each of frames 1010 as a periodical transmission timing
of the CQI by the UE 632.
[0094] First, the UE 623 transmits, to the eNB 610, a PUCCH
including the CQI and a PUSCH including uplink user data from the
UE 632 to the eNB 610 in the CQI transmission timing 1061 (step
S1001). For example, the UE 632 measures downlink reception quality
based on a radio signal from the eNB 610 to the UE 632, generates a
CQI which is an indicator of the measured reception quality, and
transmits a PUCCH including the generated CQI in step S1001.
[0095] In response to this, the eNB 610 performs the AFC based on
the CQI included in the PUCCH received in step S1001. That is, the
eNB 610 estimates a frequency deviation in the CQI included in the
received PUCCH, and compensates for, based on the estimated
frequency deviation, a frequency deviation in the PUSCH received in
step S1001.
[0096] Further, the eNB 610 calculates, as the throughput,
reception quality based on the decoding result of the PUSCH for
which the frequency deviation is compensated for by the AFC. As the
reception quality, for example, the bit error rate (BER) and the
block error ratio (BLER) may be used. Then, the eNB 610 determines
based on the calculated throughput whether to increase, decrease or
maintain the CQI transmission power from the UE 632, and generates
the TPC value based on the determination result.
[0097] Next, the eNB 610 transmits a physical downlink control
channel (PDCCH) including the generated TPC value to the UE 632
(step S1002). For example, the eNB 610 performs step S1002 in a
timing 1071 when the PDCCH is allocated to the UE 632.
[0098] Next, the UE 623 transmits, to the eNB 610, a PUSCH
including uplink user data from the UE 632 to the eNB 610 (step
S1003). In this case, a timing 1072 of step S1003 is not a
periodical transmission timing of the CQI by the UE 632 set by the
eNB 610. Therefore, the UE 632 does not transmit the PUCCH
including the CQI in step S1003.
[0099] In response to this, the eNB 610 compensates for a frequency
deviation in the PUSCH received in step S1003 by the AFC. At that
time, the eNB 610 uses the frequency deviation estimated based on
the CQI included in the PUCCH received in step S1001, in the AFC
for the PUSCH received in step S1003. Thus, the UE 632
intermittently transmits the CQI to the eNB 610 in accordance with
the setting by the eNB 610. In response to this, the eNB 610
continuously uses a value (estimated value of frequency deviation)
of the AFC calculated from the received CQI in the AFC until
receiving a next CQI.
[0100] Next, assume that a next timing is a transmission timing
next to a transmission timing in step S1001 among CQI transmission
timings by the UE 632 set by the eNB 610, that is, the CQI
transmission timing 1062. In this case, the UE 623 transmits, to
the eNB 610, a PUCCH including the CQI and a PUSCH including uplink
user data from the UE 632 to the eNB 610 (step S1004). The UE 632
adjusts the CQI transmission power included in the PUCCH
transmitted in step S1004 based on a TPC value included in the
PDCCH received in step S1002.
[0101] In response to this, the eNB 610 performs the AFC based on
the CQI included in the PUCCH received in step S1004. That is, the
eNB 610 estimates a frequency deviation in the CQI included in the
received PUCCH, and compensates for, based on the estimated
frequency deviation, a frequency deviation in the PUSCH received in
step S1004.
[0102] Further, the eNB 610 calculates, as the throughput,
reception quality based on the decoding result of the PUSCH whose
frequency deviation is compensated for by the AFC. Then, the eNB
610 detects a change of the throughput due to adjustment of the CQI
transmission power from the UE 632 based on the calculated
throughput.
[0103] Then, when the throughput has deteriorated due to adjustment
of the CQI transmission power or when there are no changes in the
throughput despite increase of the CQI transmission power, the eNB
610 restores the CQI transmission power from to the UE 632 to a
pre-adjustment transmission power. Even when restoring the CQI
transmission power from the UE 632 to the pre-adjustment
transmission power, the eNB 610 may use the TPC value included in
the PDCCH transmitted to the UE 632 in the same manner as step
S1001.
[0104] When the throughput is improved by adjustment of the CQI
transmission power or when the throughput has not deteriorated
despite decrease of the CQI transmission power, the eNB 610 does
not restore the CQI transmission power from the UE 632 to the
pre-adjustment transmission power. Then, in the same manner as step
S1002, the eNB 610 generates the TPC value based on the calculated
throughput and transmits the PDCCH including the generated TPC to
the UE 632.
[0105] Thus, upon adjusting the CQI transmission power from the UE
632, the eNB 610 checks adjustment effects of the CQI transmission
power by detecting a change of the throughput by adjustment of the
CQI transmission power from the UE 632. Then, when the throughput
has deteriorated due to adjustment of the CQI transmission power or
when there are no changes in the throughput despite increase of the
CQI transmission power, the eNB 610 restores the CQI transmission
power from to the UE 632 to the pre-adjustment transmission power.
Thus, for example, when the throughput has deteriorated due to a
factor different from deterioration of the reception quality of the
CQI, the CQI transmission power may be restored to the
pre-adjustment transmission power.
[0106] Next, adjustment of the CQI transmission power in the PUCCH
is described. In the transmission of the PUCCH, a different format
(pucch format 1, pucch format 1a, . . . , etc.) is used according
to the information transmitted by the PUCCH. The format of the
PUCCH is specified, for example, in TS36.213 of the 3rd Generation
Partnership Project (3GPP).
[0107] The UE may adjust transmission power of the CQI only in the
PUCCH by adjusting transmission power of the PUCCH only of the
format in which the CQI is transmitted. Also, when the CQI is
transmitted, for example, in the format 2x which is a format of the
PUCCH, the UE may adjust transmission power of the CQI only in the
PUCCH by adjusting the bit number of the CQI.
[0108] However, adjustment of the CQI transmission power is not
limited to adjustment of the CQI only in the PUCCH, but may be
adjustment of transmission power (for example, entire transmission
power of the PUCCH) including data different from the CQI in the
PUCCH as well.
[0109] FIG. 11 is a flowchart illustrating an example of a power
adjustment processing by the eNB according to the embodiment. Every
time receiving the PUCCH (upon receipt of the PUCCH), the eNB 610
according to the embodiment performs a processing illustrated in
FIG. 11 for UEs which have transmitted the CQI by the received
PUCCH, as target UEs. Further, the eNB 610 performs the processing
illustrated in FIG. 11 for each of cells formed by the base
station.
[0110] First, the eNB 610 calculates the throughput of a target UE
(step S1101). In step S1101, for example, the eNB 610 performs the
AFC compensating for a frequency deviation of the PUSCH received
from the target UE by then based on the CQI which the target UE has
transmitted by the received PUCCH. Then, the eNB 610 calculates, as
the throughput, reception quality based on the decoding result of
the PUSCH for which the frequency deviation is compensated for.
[0111] Next, the eNB 610 determines whether the throughput
calculated in step S1101 is lower than a predetermined threshold
value (step S1102). Thus, it may be indirectly determined whether
reception quality of the CQI included in the PUCCH from the target
UE has deteriorated. When the throughput is lower than the
threshold value (step S1102: Yes), the eNB 610 determines whether
the number of times of throughput check trials of the target UE is
larger than a predetermined threshold value (step S1103). The
number of times of throughput check trials of the target UE is the
number of times of check trials of throughput of the target UE, and
the default value thereof is 0.
[0112] In step S1103, when the number of times of throughput check
trials is not larger than the threshold value (step S1103: No), the
eNB 610 counts up (+1) the number of times of throughput check
trials of the target UE (step S1104).
[0113] Next, the eNB 610 determines whether the CQI transmission
power adjustment execution flag (up) of the target UE is ON (step
S1105). The CQI transmission power adjustment execution flag (up)
is information indicating whether adjustment of the CQI
transmission power for the target UE is being executed. In the
initialized state, the CQI transmission power adjustment execution
flag is set to OFF. When the CQI transmission power adjustment
execution flag (up) is not ON (step S1105: No), the eNB 610 ends a
series of processings for the target UE.
[0114] In step S1103, when the number of times of throughput check
trials is larger than a threshold value (step S1103: Yes), the eNB
610 initializes the number of times of throughput check trials of
the target UE (step S1106). That is, the eNB 610 resets the number
of times of throughput check trials of the target UE to 0.
[0115] Next, the eNB 610 holds the throughput of the target UE
calculated in step S1101 and a current CQI transmission power
(pre-adjustment CQI transmission power) of the target UE into the
memory (step S1107). The memory holding the throughput and the CQI
transmission power of the target UE may be, for example, a memory
322 illustrated in FIG. 3.
[0116] Next, the eNB 610 performs adjustment of increasing the CQI
transmission power of the target UE (step S1108). The processing of
adjustment of increasing the CQI transmission power of the target
UE in step S1108 is described later (for example, see FIG. 12).
Next, the eNB 610 turns ON the CQI transmission power adjustment
execution flag (up) of the target UE (step S1109) and ends a series
of processings for the target UE.
[0117] In step S1105, when the CQI transmission power adjustment
execution flag (up) is ON (step S1105: Yes), the eNB 610 performs
adjustment of increasing the CQI transmission power of the target
UE (step S1110) and ends a series of processings for the target UE.
The processing of adjustment of increasing the CQI transmission
power of the target UE in step S1110 is the same as step S1108 and
described later (for example, see FIG. 12).
[0118] In step S1102, when the throughput is not lower than the
threshold value (step S1102: No), the eNB 610 performs adjustment
of decreasing the CQI transmission power of the target UE (step
S1111). The processing of adjustment of decreasing the CQI
transmission power of the target UE in step S1111 is described
later (for example, see FIG. 15). Next, the eNB 610 turns ON the
CQI transmission power adjustment execution flag (down) of the
target UE (step S1112) and ends a series of processings for the
target UE.
[0119] The number of times of throughput check trials used in step
S1103 may be set, for example, according to the number of UEs
(multiplex number of PUCCH) which have transmitted the CQI by the
received PUCCH. For example, the number of times of throughput
check trials is set smaller as the multiplex number of the PUCCH is
larger. This is because that as the multiplex number of the PUCCH
is larger, decrease in the throughput of the PUSCH may cause
decrease in the AFC accuracy with high possibility.
[0120] That is, in case that the multiplex number of the PUCCH is
large, decrease in the throughput may be improved at an early stage
by adjusting so as to increase the CQI transmission power at an
early stage. In a case that the multiplex number of the PUCCH is
small, even when throughput drops, control may be stabilized by
delaying the adjustment of increasing the CQI transmission power.
Thus, throughput may be improved efficiently by setting a smaller
number of times of throughput check trials with respect to a larger
multiplex number of the PUCCH.
[0121] FIG. 12 is a flowchart illustrating an example of a
processing of adjustment of increasing the CQI transmission power
of the target UE by the eNB according to the embodiment. In steps
S1108 and S1110 illustrated in FIG. 11, the eNB 610 performs, for
example, a processing illustrated in FIG. 12 as a processing of
adjustment of increasing the CQI transmission power of the target
UE.
[0122] First, the eNB 610 searches for a UE having a CQI
transmission timing same as the target UE out of UEs coupled to the
cell thereof (step S1201). Next, the eNB 610 determines based on
the search result in step S1201 whether there is a UE having a CQI
transmission timing same as the target UE (step S1202).
[0123] In step S1202, when determined that there is a UE having a
CQI transmission timing same as the target UE (step S1202: Yes),
the eNB 610 shifts to step S1203. That is, the eNB 610 determines
whether the CQI transmission power of the target UE is largest
among UEs which transmit the CQI in the CQI transmission timing of
the target UE (step S1203). When the CQI transmission power of the
target UE is largest (step S1203: Yes), it may be determined that
there is a high possibility that the throughput of the target UE is
not improved even when the CQI transmission power of the target UE
is increased. In this case, the eNB 610 ends a series of adjustment
processings.
[0124] In step S1203, when the CQI transmission power of the target
UE is not largest (step S1203: No), the eNB 610 shifts to step
S1204. That is, the eNB 610 searches for a UE having a largest CQI
transmission power among UEs which transmit the CQI in the CQI
transmission timing of the target UE (step S1204). For example, the
eNB 610 stores the CQI transmission power for each of UEs (for
example, see FIG. 18) and may perform searching of step S1204 based
on the CQI transmission power for each of UEs.
[0125] Next, the eNB 610 sets the CQI transmission power of a UE
having a largest transmission power identified by searching in step
S1204 as a target power of the target UE (step S1205). That is, in
the CQI transmission timing of the target UE, the UE identified by
the searching is considered a largest interference source. Thus,
interference with the target UE may be canceled by matching the CQI
transmission timing of the target UE with the largest interference
source.
[0126] Next, the eNB 610 performs power adjustment (up) based on
the target power set in step S1205 (step S1206) and ends a series
of adjustment processings. Processing of power adjustment (up)
based on the target power in step S1206 is described later (for
example, see FIGS. 13 and 14).
[0127] In step S1202, when the eNB 610 determines that there are no
UEs having the same CQI transmission timing (step S1202: No), only
the target UE transmits the CQI in the CQI transmission timing of
the target UE. That is, it may be determined that there is no
deterioration of the CQI due to transmission of the CQI by multiple
UEs. In this case, the eNB 610 does not perform adjustment of
increasing the CQI transmission power of the target UE and ends a
series of adjustment processings.
[0128] Thus, when throughput (reception quality) of the PUSCH (data
signal) from the target UE subjected to the AFC is lower than a
threshold value (predetermined reception quality), the eNB 610
identifies a UE having a largest CQI transmission power among other
UEs having the same transmission timing as the target UE. Then, the
eNB 610 performs adjustment of increasing the CQI transmission
power of the target UE based on the transmission power of the
identified UE. Thus, the CQI transmission power of the target UE
may be adjusted so as to match with the CQI transmission power of a
UE which may be a largest interference source in the CQI
transmission timing of the target UE with high possibility, and
thereby interference with the CQI by the target UE may be
reduced.
[0129] When there are no UEs having the same transmission timing as
the target UE and having a CQI transmission power higher than the
target UE, the eNB 610 does not perform adjustment of increasing
the transmission power of the target UE. Thus, although there is a
low possibility of improving throughput of the target UE even by
performing adjustment of increasing the transmission power of the
target UE, growing interference with the CQI of other UEs may be
suppressed by increasing the CQI transmission power of the target
UE.
[0130] FIG. 13 is a flowchart illustrating an example of a
processing of power adjustment (up) based on the target power by
the eNB according to the embodiment. In step S1206 illustrated in
FIG. 12, the eNB 610 performs, for example, a processing
illustrated in FIG. 13 as a processing of power adjustment (up)
based on the target power. First, the eNB 610 determines whether
data type of the target UE is voice over LTE (VoLTE) (step
S1301).
[0131] In step S1301, in a case that the data type is VoLTE (step
S1301: Yes), it may be determined that priority is preferably given
to improvement of the AFC accuracy in the target UE. In this case,
the eNB 610 adjusts the CQI transmission power of the target UE so
as to be the target power set in step S1205 (step S1302) and ends a
series of power adjustment processings. Thus, the AFC accuracy in
the target UE may be improved by increasing the CQI transmission
power of the target UE in a short time.
[0132] In step S1301, when the date type is not VoLTE (step S1301:
No), the eNB 610 determines whether the target UE is moving at a
high speed (step S1303). The determination in step S1303 may be
made, by way of an example, based on fading fluctuation for the
target UE estimated by the eNB 610. However, the determination in
step S1303 is not limited to such a method, and may be made, for
example, from detection result of the moving state of the target UE
which the eNB 610 receives from the target UE.
[0133] In step S1303, in a case that the UE is moving at a high
speed (step S1303: Yes), the eNB 610 determines that the target UE
may be outside the cell of the eNB 610 in a short time. Thus, the
eNB 610 does not perform adjustment of increasing the CQI
transmission power of the target UE and ends a series of power
adjustment processings.
[0134] In step S1303, in a case that the UE is not moving at a high
speed (step S1303: No), the eNB 610 shifts to step S1304. That is,
the eNB 610 increases the CQI transmission power of the target UE
by a predetermined unit with the target power set in step S1205
illustrated in FIG. 12 as an upper limit (step S1304) and ends a
series of power adjustment processings. Thus, the eNB 610 performs
ramping of gradually increasing the CQI transmission power of the
target UE. Thus, speed of adjusting the CQI transmission power of
the target UE may be reduced and thereby the CQI transmission power
of the target UE may not become much larger than other UEs.
[0135] Thus, the eNB 610 sets the power adjustment method, for
example, according to the state (data type or moving state) of the
target UE. Adjustment of the transmission power in steps S1302 and
S1304 may be performed, for example, by using uplink (UL) control
information such as the TPC value transmitted to the target UE.
[0136] That is, in the adjustment of the CQI transmission power of
the target UE, the eNB 610 sets adjustment speed of the CQI
transmission power of the target UE based on the type of data
signal transmitted from the target UE to the eNB 610. Thus,
transmission power may be increased for the CQI used in the AFC of
the data signal having high priority, and thereby throughput of the
data signal having high priority may be improved preferentially.
Further, transmission power may be reduced for the CQI used in the
AFC of the data signal of the type having low priority, and thereby
interference with the CQI of other UEs may be reduced.
[0137] When the target UE is moving at a speed equal to or higher
than a predetermined speed (moving at high speed), the eNB 610 does
not perform adjustment of increasing the CQI transmission power of
the target UE even if throughput for the target UE is lower than
the threshold value (predetermined reception quality). Thus,
adjustment of the CQI transmission power for the target UE which
may be outside the cell's region in a short time with high
possibility may be suppressed, and thereby control of the CQI
transmission power of each UE may be stabilized.
[0138] FIG. 14 is a flowchart illustrating an example of a
processing of power adjustment (up) based on the target power by
the eNB according to the embodiment. In step S1206 illustrated in
FIG. 12, the eNB 610 may perform, for example, a processing
illustrated in FIG. 14 as a processing of power adjustment (up)
based on the target power. First, the eNB 610 determines whether
priority of the data type of the target UE is higher than any UEs
having the same transmission timing as the target UE (step S1401).
A UE having the same CQI transmission timing as the target UE is,
for example, a UE identified by searching in step S1201 illustrated
in FIG. 12.
[0139] In step S1401, when priority of the data type of the target
UE is higher than any other UEs (step S1401: Yes), the eNB 610
shifts to step S1402. That is, the eNB 610 increases the CQI
transmission power of the target UE by a predetermined unit (large)
with the target power set in step S1205 illustrated in FIG. 12 as
an upper limit (step S1402) and ends a series of power adjustment
processings. The predetermined unit for increasing the transmission
power in step S1402 is, for example, a larger unit than in step
S1404. Thus, adjustment speed of the CQI transmission power of the
target UE becomes faster relatively.
[0140] In step S1401, when priority of the data type of the target
UE is lower than or same as any other UEs (step S1401: No), the eNB
610 shifts to step S1403. That is, the eNB 610 determines whether
there is a UE having a priority of the data type higher than the
target UE among UEs having the same transmission timing as the
target UE (step S1403).
[0141] In step S1403, when determined that there is a UE having a
priority of the data type higher than the target UE (step S1403:
Yes), the eNB 610 shifts to step S1404. That is, the eNB 610
increases the CQI transmission power of the target UE by a
predetermined unit (small) with the target power as an upper limit
(step S1404) and ends a series of power adjustment processings. The
predetermined unit for increasing the transmission power in step
S1404 is, for example, a smaller unit than in steps S1402 and
S1406. Thus, adjustment speed of the CQI transmission power of the
target UE becomes slower relatively.
[0142] In step S1403, when determined that there are no UEs having
a priority of the data type higher than the target UE (step S1403:
No), the eNB 610 determines whether the number of times of
adjustment (up) of the target UE is one (step S1405). The number of
times of adjustment (up) is the number of upward adjustment
executions of the CQI transmission power of the target UE. For
example, default value of the number of times of adjustment (up) is
"0", which is counted up every time the eNB 610 shifts to step
S1206 illustrated in FIG. 12.
[0143] In step S1405, when the number of times of adjustment (up)
is one (step S1405: Yes), the eNB 610 shifts to step S1406. That
is, the eNB 610 increases the CQI transmission power of the target
UE by a predetermined unit (large) with the target power as an
upper limit (step S1406) and ends a series of power adjustment
processings. The predetermined unit for increasing the transmission
power in step S1406 is, for example, a larger unit than in step
S1404. Thus, adjustment speed of the CQI transmission power of the
target UE becomes faster relatively.
[0144] In step S1405, when the number of times of adjustment (up)
is not one (step S1405: No), the eNB 610 shifts to step S1407. That
is, the eNB 610 determines whether the number of times of
adjustment (up) of the target UE is smallest among UEs which
transmit the CQI in the CQI transmission timing of the target UE
(step S1407).
[0145] In step S1407, when the number of times of adjustment (up)
of the target UE is smallest (step S1407: Yes), the eNB 610 shifts
to step S1406. When the number of times of adjustment (up) of the
target UE is not smallest (step S1407: No), the eNB 610 shifts to
step S1408. That is, the eNB 610 adjusts the CQI transmission power
of the target UE so as to be the target power set in step S1205
(step S1408) and ends a series of power adjustment processings.
[0146] The processing of power adjustment (up) based on the target
power in step S1206 illustrated in FIG. 12 is not limited to
processings illustrated in FIG. 13 and FIG. 14, and various
modifications may be possible. For example, in step S1403
illustrated in FIG. 14, when determined that there are no UEs
having priority of the data type higher than the target UE, the eNB
610 may not perform adjustment of increasing the CQI transmission
power of the target UE and end a series of power adjustment
processings. Further, the priority is not limited to the priority
of the data type, but may be various priorities such as, for
example, a user contract plan of the target UE.
[0147] Here, an example of the data type and priority is described.
For example, as the No. 1 rank data type having highest priority,
there is an emergency call and medical information. As a rank No. 2
data type following the rank No. 1, there is, for example, a voice
call by VoLTE.
[0148] As a rank No. 3 data type following the rank No. 2, there
is, for example, a web data (web information) and application data
(Appli) by the web browser. As a rank No. 4 data type following the
rank No. 3, there is, for example, sensing data from a sensor node
from a sensor network.
[0149] Thus, the eNB 610 sets adjustment speed of the CQI
transmission power of the target UE based on the type of the data
signal from the target UE to the eNB 610 and the type of the data
signal from the target UE to a different UE. Thus, transmission
power may be increased for the CQI used in the AFC of the data
signal having the priority higher than other UEs, and thereby
throughput of the data signal having higher priority may be
improved preferentially. Also, transmission power may be reduced
for the CQI used in the AFC of the data signal of a type having the
priority lower than other UEs, and thereby interference with the
CQI of other UEs may be reduced.
[0150] The eNB 610 sets adjustment speed of the CQI transmission
power of the target UE based on number of times of adjustment of
the CQI transmission power for the target UE. Thus, CQI
transmission power is adjusted preferentially, for example, for a
UE having a less number of times of adjustment of the CQI
transmission power and having a high possibility of throughput
improvement by increase of the CQI transmission power, and thereby
throughput within the cell of the eNB 610 may be improved
efficiently.
[0151] The eNB 610 sets adjustment speed of the CQI transmission
power of the target UE based on the number of times of adjustment
of the CQI transmission power for the target UE and the number of
times of adjustment of the CQI transmission power for a terminal
device different from the target UE. Thus, the CQI transmission
power is adjusted preferentially, for example, for a UE having a
less number of times of adjustment of the CQI transmission power
and having a high possibility of throughput improvement by increase
of the CQI transmission power, and thereby throughput within the
cell of the eNB 610 may be improved efficiently.
[0152] FIG. 15 is a flowchart illustrating an example of a
processing of adjustment of decreasing the CQI transmission power
of the target UE by the eNB according to the embodiment. In step
S1111 illustrated in FIG. 11, the eNB 610 performs, for example, a
processing illustrated in FIG. 15 as the processing of adjustment
of decreasing the CQI transmission power of the target UE.
[0153] Steps S1501 and S1502 illustrated in FIG. 15 are similar
with steps S1201 and S1202 illustrated in FIG. 12. In step S1502,
when determined that there is a UE having a CQI transmission timing
same as the target UE (step S1502: Yes), the eNB 610 shifts to step
S1503. That is, the eNB 610 determines whether the CQI transmission
power of the target UE is largest among UEs which transmit the CQI
in the CQI transmission timing of the target UE (step S1503).
[0154] In step S1503, when CQI transmission power of the target UE
is not largest (step S1503: No), it may be determined that the
target UE is not a large interference source in the CQI
transmission timing of the target UE. In this case, the eNB 610
does not reduce the CQI transmission power of the target UE and
ends a series of adjustment processings.
[0155] In step S1503, when the CQI transmission power of the target
UE is largest (step S1503: Yes), it may be determined that the
target UE may be a large interference source in the CQI
transmission timing of the target UE. In this case, the eNB 610
performs a predetermined power adjustment (down) (step S1504) and
ends a series of adjustment processings. Power adjustment (down)
processing in step S1504 is described later (for example, see FIG.
16).
[0156] Thus, when throughput (reception quality) of the PUSCH (data
signal) from the target UE subjected to the AFC is equal to or
higher than a threshold value (predetermined reception quality) and
the CQI transmission power of the target UE is largest, the eNB 610
performs adjustment of decreasing the CQI transmission power of the
target UE. Thus, when there is a high possibility that the target
UE is a largest interference source in the CQI transmission timing
of the target UE, interference with other UEs by the CQI of the
target UE may be reduced by reducing the CQI transmission power of
the target UE.
[0157] FIG. 16 is a flowchart illustrating an example of a power
adjustment (down) processing by the eNB according to the
embodiment. In step S1504 illustrated in FIG. 15, the eNB 610
performs, for example, a processing illustrated in FIG. 16 as a
power adjustment (down) processing. First, the eNB 610 determines
whether priority of the data type of the target UE is higher than
any UEs having the same CQI transmission timing as the target UE
(step S1601).
[0158] In step S1601, when priority of the data type of the target
UE is higher than any other UEs (step S1601: Yes), the eNB 610
shifts to step S1602. That is, the eNB 610 reduces the CQI
transmission power of the target UE by a predetermined unit (small)
(step S1602) and ends a series of power adjustment processings. The
predetermined unit for reducing the transmission power in step
S1602 is, for example, a smaller unit than in step S1605.
[0159] In step S1601, when priority of the data type of the target
UE is lower than or same as any other UEs (step S1601: No), the eNB
610 shifts to step S1603. That is, the eNB 610 determines whether
there is a UE having a priority of the data type higher than the
target UE among UEs having the same CQI transmission timing as the
target UE (step S1603).
[0160] In step S1603, when determined that there is a UE having
priority of the data type higher than the target UE (step S1603:
Yes), the eNB 610 shifts to step S1604. That is, the eNB 610 sets
the CQI transmission power of a UE (concerned UE) having priority
of the data type higher than the target UE as a target power of the
CQI transmission power of the target UE (step S1604).
[0161] Next, the eNB 610 reduces CQI transmission power of the
target UE by a predetermined unit (large) with the target power set
in step S1604 as an upper limit (step S1605) and ends a series of
power adjustment processings. The predetermined unit for reducing
the transmission power in step S1605 is, for example, a unit larger
than in steps S1602 and S1606.
[0162] In step S1603, when determined that there are no UEs having
priority of the data type higher than the target UE (step S1603:
No), the eNB 610 shifts to step S1606. That is, the eNB 610 reduces
the CQI transmission power of the target UE by a predetermined unit
(small) (step S1606) and ends a series of power adjustment
processings. The predetermined unit for reducing the transmission
power in step S1606 is, for example, a smaller unit than in step
S1605.
[0163] FIGS. 17 and 18 are flowcharts illustrating an example of a
power adjustment check processing by the eNB according to the
embodiment. Every time receiving the PUCCH (upon receiving the
PUCCH), the eNB 610 may perform processings illustrated in FIG. 17
and FIG. 18 along with the processing illustrated in FIG. 11 for
each of UEs which has transmitted the CQI in the received PUCCH, as
the target UE. For example, every time receiving the PUCCH, the eNB
610 performs processings illustrated in FIGS. 17 and 18 for each of
UEs and then performs the processing illustrated in FIG. 11 for
each of UEs. The eNB 610 performs processings illustrated in FIGS.
17 and 18 for each of cells formed by the base station.
[0164] First, the eNB 610 calculates throughput of the target UE
(step S1701). The throughput calculation processing in step S1701
is the same as the throughput calculation processing in step S1101
illustrated in FIG. 11. Next, the eNB 610 determines whether the
CQI transmission power adjustment execution flag (up) of the target
UE is ON (step S1702). The CQI transmission power adjustment
execution flag (up) is set ON, for example, in step S1109
illustrated in FIG. 11.
[0165] In step S1702, when the CQI transmission power adjustment
execution flag (up) is ON (step S1702: Yes), the eNB 610 determines
whether throughput of the target UE is improved (step S1703). The
determination in step S1703 may be made by comparing pre-adjustment
throughput of the target UE held in step S1107 illustrated in FIG.
11 and current throughput of the target UE calculated in step S1702
with each other. The eNB 610 also may determine in step S1703
whether throughput of the target UE is improved by a specific
amount or more.
[0166] In step S1703, when the throughput is not improved (step
S1703: No), the eNB 610 determines whether the number of times of
throughput improvement check trials of the target UE is larger than
a predetermined threshold value (step S1704). The number of times
of throughput improvement check trials of the target UE is the
number of times of check trials of throughput improvement of the
target UE, and the default value thereof is 0. When the number of
times of throughput improvement check trials is not larger than the
threshold value (step S1704: No), the eNB 610 shifts to step S1705.
That is, the eNB 610 counts up (+1) the number of times of
throughput improvement check trials of the target UE (step S1705),
and ends a series to power adjustment processings.
[0167] In step S1704, when the number of times of throughput
improvement check trials is larger than the threshold value (step
S1704: Yes), the eNB 610 restores the CQI transmission power of the
target UE to the pre-adjustment CQI transmission power of the
target UE (step S1706). The pre-adjustment CQI transmission power
of the target UE is, for example, the CQI transmission power of the
target UE held in step S1107 illustrated in FIG. 11.
[0168] Next, the eNB 610 turns OFF the CQI transmission power
adjustment execution flag (up) of the target UE (step S1707).
Further, the eNB 610 initializes the number of times of throughput
improvement check trials of the target UE (step S1708). That is,
the eNB 610 resets the number of times of throughput improvement
check trials of the target UE to 0. Further, the eNB 610 clears
throughput of the target UE held in step S1107 illustrated in FIG.
11 (step S1709) and ends a series of processings for the target
UE.
[0169] In step S1703, when the throughput is improved (step S1703:
Yes), the eNB 610 turns OFF the CQI transmission power adjustment
execution flag (up) of the target UE (step S1710). Further, the eNB
610 initializes the number of times of throughput improvement check
trials of the target UE (step S1711). That is, the eNB 610 resets
the number of times of throughput improvement check trials of the
target UE to 0. Further, the eNB 610 clears throughput of the
target UE held in step S1107 illustrated in FIG. 11 (step S1712)
and ends a series of processings for the target UE.
[0170] In step S1702, when the CQI transmission power adjustment
execution flag (up) is not ON (step S1702: No), the eNB 610
determines whether the CQI transmission power adjustment execution
flag (down) of the target UE is ON (step S1713). The CQI
transmission power adjustment execution flag (down) is set ON, for
example, in step S1112 illustrated in FIG. 11.
[0171] In step S1713, when the CQI transmission power adjustment
execution flag (down) is not ON (step S1713: No), the eNB 610 ends
a series of processings for the target UE. When the CQI
transmission power adjustment execution flag (down) is ON (step
S1713: Yes), the eNB 610 determines whether throughput of the
target US has deteriorated (step S1714). The determination in step
S1714 may be made by comparing pre-adjustment throughput of the
target UE held in step S1107 illustrated in FIG. 11 and current
throughput of the target UE calculated in step S1702 with each
other. Further, the eNB 610 may determine in step S1714 whether
throughput of the target UE has deteriorated by a specific amount
or more.
[0172] In step S1714, when the throughput has not deteriorated
(step S1714: No), the eNB 610 determines whether the number of
times of throughput no-change check trials of the target UE is
larger than a predetermined threshold value (step S1715). The
number of times of throughput no-change check trials is information
indicating that the number of times of checking whether throughput
has not deteriorated due to adjustment of decreasing the CQI
transmission power of the target UE.
[0173] In step S1715, when the number of times of throughput
no-change check trials is not larger than the threshold value (step
S1715: No), the eNB 610 shifts to step S1716. That is, the eNB 610
counts up (+1) the number of times of throughput no-change check
trials of the target UE (step S1716), and ends a series of power
adjustment processings for the target UE.
[0174] In step S1715, when the number of times of throughput
no-change check trials is larger than the threshold value (step
S1715: Yes), the eNB 610 turns OFF the CQI transmission power
adjustment execution flag (down) of the target UE (step S1717).
Further, the eNB 610 initializes the number of times of throughput
no-change check trials of the target UE (step S1718). That is, the
eNB 610 resets the number of times of throughput no-change check
trials of the target UE to 0. Further, the eNB 610 clears
throughput of the target UE held in step S1107 illustrated in FIG.
11 (step S1719) and ends a series of processings for the target
UE.
[0175] In step S1714, when the throughput has deteriorated (step
S1714: Yes), the eNB 610 restores the CQI transmission power of the
target UE to the pre-adjustment CQI transmission power of the
target UE (step S1720). The pre-adjustment CQI transmission power
of the target UE is, for example, the CQI transmission power of the
target UE held in step S1107 illustrated in FIG. 11.
[0176] Further, the eNB 610 turns OFF the CQI transmission power
adjustment execution flag (down) of the target UE (step S1721).
Further, the eNB 610 initializes the number of times of throughput
no-change check trials of the target UE (step S1722). That is, the
eNB 610 resets the number of times of throughput no-change check
trials of the target UE to 0. Further, the eNB 610 clears
throughput of the target UE held in step S1107 illustrated in FIG.
11 (step S1723) and ends a series of processings for the target
UE.
[0177] Thus, when the adjustment of the CQI transmission power is
performed, the eNB 610 compares pre-adjustment and post-adjustment
throughputs with each other, and based on a result the comparison,
restores the CQI transmission power to the pre-adjustment CQI
transmission power if there are no effects of the adjustment of the
CQI transmission power. Thus, continuous adjustment of the CQI
transmission power despite no improvements of the throughput by
adjustment of the CQI transmission power may be avoided and thereby
control of the transmission power of each UE may be stabilized.
[0178] The number of times of throughput improvement check trials
used in step S1704 may be set according to the cycle of the CQI
transmission timing of the target UE. For example, the number of
times of throughput improvement check trials is set larger as the
cycle of the CQI transmission timing of the target UE is shorter.
In this case, as the cycle of the CQI transmission timing of the
target UE is shorter, adjustment width of the CQI transmission
power may be made smaller.
[0179] FIG. 19 is a diagram illustrating an example of information
of each of UEs stored by the eNB according to the embodiment. The
eNB 610 stores, for example, UE information 1900 illustrated in
FIG. 19 in the memory as information of each of UEs. The UE
information 1900 includes, for each of UEs (UE #1 to UE #X) coupled
to the cell of the base station, the CQI transmission timing,
throughput, transmission power and the numbers of times of various
trials and processing flags. The CQI transmission timing is a
timing (CQI transmission cycle) when a corresponding UE transmits
the CQI to the eNB 610.
[0180] The throughput includes pre-adjustment throughput of the CQI
transmission power for the target UE and current throughput
(post-adjustment throughput of CQI transmission power). The
pre-adjustment throughput of the CQI transmission power for the
target UE is, for example, the throughput held in step S1107
illustrated in FIG. 11. The current throughput (post-adjustment
throughput of CQI transmission power) of the target UE is, for
example, the throughput calculated in step S1107 illustrated in
FIG. 17 and FIG. 18.
[0181] The transmission power includes the pre-adjustment CQI
transmission power for the target UE and current (post-adjustment)
CQI transmission power of the target UE. The pre-adjustment CQI
transmission power for the target UE is, for example, the CQI
transmission power held in step S1107 illustrated in FIG. 11. The
current (post-adjustment) transmission power of the target UE is,
for example, the post-adjustment CQI transmission power calculated
in steps S1108, S1110 and S1111 illustrated in FIG. 11.
[0182] The numbers of times of various trials and processing flags
include the number of times of throughput check trials, the number
of times of throughput improvement check trials, the number of
times of throughput no-change check trials, the number of times of
adjustment (up), CQI transmission power adjustment execution flag
(up) and CQI transmission power adjustment execution flag (down).
The number of times of throughput check trials is counted up, for
example, in step S1104 illustrated in FIG. 11. The number of times
of throughput check trials is initialized, for example, in step
S1106 illustrated in FIG. 11.
[0183] The number of times of throughput improvement check trials
is counted up, for example, in step S1105 illustrated in FIG. 17
and FIG. 18 with the default Value of 0. The number of times of
throughput no-change check trials is counted up, for example, in
step S1716 illustrated in FIG. 17 and FIG. 18 with the default
value of 0. The number of times of adjustment (up) is counted up
every time the eNB 610 shifts, for example, to step S1206
illustrated in FIG. 12, with the default value of 0.
[0184] The CQI transmission power adjustment execution flag (up) is
set ON, for example, in step S1109 illustrated in FIG. 11 with the
default value of OFF. The CQI transmission power adjustment
execution flag (up) is set OFF, for example, in steps S1707 and
S1710 illustrated in FIG. 17 and FIG. 18. The CQI transmission
power adjustment execution flag (down) is set ON, for example, in
step S1112 illustrated in FIG. 11 with the default value of OFF.
Further, the CQI transmission power adjustment execution flag
(down) is set OFF, for example, in steps S1717 and S1721
illustrated in FIG. 17 and FIG. 18.
[0185] Thus, the eNB 610 according to the embodiment adjusts the
CQI transmission power from the target UE based on the CQI
transmission power from each of UEs whose CQI transmission timing
is the same as the target UE. Thus, the transmission power of each
of CQIs multiplexed in the same timing may be matched, and thereby
interference among the CQIs may be reduced. Therefore, decrease in
the AFC accuracy based on the CQI may be suppressed especially in
an overcrowded communication environment with high cell in/out
traffic, or in an environment where many CQIs are multiplexed in
the PUCCH.
[0186] As described above, the base station apparatus may suppress
decrease in the AFC accuracy. Although the above embodiment is
described by using a predetermined signal used in the AFC as an
example, the predetermined signal used in the AFC is not limited to
the CQI. For example, the predetermined signal used in the AFC may
be a signal which is periodically multiplexed and transmitted at
the same timing by a plurality of terminal devices.
[0187] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the invention and the concepts contributed by the
inventor to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions, nor does the organization of such examples in the
specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiments of the
present invention have been described in detail, it should be
understood that the various changes, substitutions, and alterations
could be made hereto without departing from the spirit and scope of
the invention.
* * * * *